logback.xml file
The logback.xml configuration file can optionally set logging levels
for the logs written to system.log and debug.log. The logging levels
can also be set using nodetool setlogginglevels.
Options
appender name="<appender_choice>"…</appender>
Specify log type and settings. Possible appender names are: SYSTEMLOG,
DEBUGLOG, ASYNCDEBUGLOG, and STDOUT. SYSTEMLOG ensures that WARN
and ERROR message are written synchronously to the specified file.
DEBUGLOG and ASYNCDEBUGLOG ensure that DEBUG messages are written
either synchronously or asynchronously, respectively, to the specified
file. STDOUT writes all messages to the console in a human-readable
format.
Example: <appender name="SYSTEMLOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file> <filename> </file>
Specify the filename for a log.
Example: <file>$\{cassandra.logdir}/system.log</file>
<level> <log_level> </level>
Specify the level for a log. Part of the filter. Levels are: ALL,
TRACE, DEBUG, INFO, WARN, ERROR, OFF. TRACE creates the
most verbose log, ERROR the least.
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Increasing logging levels can generate heavy logging output on
a moderately trafficked cluster. You can use the
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Default: INFO
Example: <level>INFO</level>
<rollingPolicy class="<rolling_policy_choice>" <fileNamePattern><pattern_info></fileNamePattern> … </rollingPolicy>
Specify the policy for rolling logs over to an archive.
Example: <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<fileNamePattern> <pattern_info> </fileNamePattern>
Specify the pattern information for rolling over the log to archive. Part of the rolling policy.
Example: <fileNamePattern>$\{cassandra.logdir}/system.log.%d{yyyy-MM-dd}.%i.zip</fileNamePattern>
<maxFileSize> <size> </maxFileSize>
Specify the maximum file size to trigger rolling a log. Part of the rolling policy.
Example: <maxFileSize>50MB</maxFileSize>
<maxHistory> <number_of_days> </maxHistory>
Specify the maximum history in days to trigger rolling a log. Part of the rolling policy.
Example: <maxHistory>7</maxHistory>
<encoder> <pattern>…</pattern> </encoder>
Specify the format of the message. Part of the rolling policy.
Example: <maxHistory>7</maxHistory> Example: <encoder> <pattern>%-5level [%thread] %date{ISO8601} %F:%L - %msg%n</pattern> </encoder>
Logging to Cassandra virtual table
It is possible to configure logback.xml in such a way that logs would appear in system_views.system_log table.
This is achieved by appender implemented in class VirtualTableAppender which is called CQLLOG in the
default configration. When the appender is commented out, no system logs are written to the virtual table.
CQLLOG appender is special as the underlying structure it saves log messages into can not grow without any bound
as a node would run out of memory. For this reason, system_log table is limited on its size.
By default, it can hold at most 50 000 log messages, it can never hold more than 100 000 log messages.
To specify how many rows you want that virtual table to hold at most, there is
a system property called cassandra.virtual.logs.max.rows which takes an integer as value.
You can execute CQL truncate query for system_views.system_log if you want to wipe out all the logs in virtual table
to e.g. save some memory.
It is recommended to set filter to at least WARN level so this table holds only important logging messages as
each message will occupy memory.
The appender to virtual table is commented out by default so logging to virtual table is not active.
Contents of default logback.xml
<configuration scan="true" scanPeriod="60 seconds">
<jmxConfigurator />
<!-- No shutdown hook; we run it ourselves in StorageService after shutdown -->
<!-- SYSTEMLOG rolling file appender to system.log (INFO level) -->
<appender name="SYSTEMLOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<level>INFO</level>
</filter>
<file>${cassandra.logdir}/system.log</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<!-- rollover daily -->
<fileNamePattern>${cassandra.logdir}/system.log.%d{yyyy-MM-dd}.%i.zip</fileNamePattern>
<!-- each file should be at most 50MB, keep 7 days worth of history, but at most 5GB -->
<maxFileSize>50MB</maxFileSize>
<maxHistory>7</maxHistory>
<totalSizeCap>5GB</totalSizeCap>
</rollingPolicy>
<encoder>
<pattern>%-5level [%thread] %date{ISO8601} %F:%L - %msg%n</pattern>
</encoder>
</appender>
<!-- DEBUGLOG rolling file appender to debug.log (all levels) -->
<appender name="DEBUGLOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${cassandra.logdir}/debug.log</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<!-- rollover daily -->
<fileNamePattern>${cassandra.logdir}/debug.log.%d{yyyy-MM-dd}.%i.zip</fileNamePattern>
<!-- each file should be at most 50MB, keep 7 days worth of history, but at most 5GB -->
<maxFileSize>50MB</maxFileSize>
<maxHistory>7</maxHistory>
<totalSizeCap>5GB</totalSizeCap>
</rollingPolicy>
<encoder>
<pattern>%-5level [%thread] %date{ISO8601} %F:%L - %msg%n</pattern>
</encoder>
</appender>
<!-- ASYNCLOG assynchronous appender to debug.log (all levels) -->
<appender name="ASYNCDEBUGLOG" class="ch.qos.logback.classic.AsyncAppender">
<queueSize>1024</queueSize>
<discardingThreshold>0</discardingThreshold>
<includeCallerData>true</includeCallerData>
<appender-ref ref="DEBUGLOG" />
</appender>
<!-- STDOUT console appender to stdout (INFO level) -->
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<level>INFO</level>
</filter>
<encoder>
<pattern>%-5level [%thread] %date{ISO8601} %F:%L - %msg%n</pattern>
</encoder>
</appender>
<!-- Uncomment bellow and corresponding appender-ref to activate logback metrics
<appender name="LogbackMetrics" class="com.codahale.metrics.logback.InstrumentedAppender" />
-->
<!-- Uncomment below configuration and corresponding appender-ref to activate
logging into system_views.system_logs virtual table. -->
<!-- <appender name="CQLLOG" class="org.apache.cassandra.utils.logging.VirtualTableAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<level>WARN</level>
</filter>
</appender> -->
<root level="INFO">
<appender-ref ref="SYSTEMLOG" />
<appender-ref ref="STDOUT" />
<appender-ref ref="ASYNCDEBUGLOG" /> <!-- Comment this line to disable debug.log -->
<!--
<appender-ref ref="LogbackMetrics" />
-->
<!--
<appender-ref ref="CQLLOG"/>
-->
</root>
<logger name="org.apache.cassandra" level="DEBUG"/>
</configuration>